Antisparking device for dynamo-electric machines.



UN iTED STATES VlearnNT ormoni.

Louis REN AUVERT Ann ALPHONSE :raANQors run-finer FERRAN or rams,

FRANCE'.

ANTISPARKING DEVICE FOR DYNAMO-ELECTRIC MACHINES.

Specification of Letters Patent.

Application filed July 95, 1908.

Patented June 23, i914.

serial No. 445.432.

T0 ./rZ 107mm i m n.1/ concern Be it known that We, LOUIS REN AUvnR'r and Anrnoxsn FRANois ERNEST FERRAND, bot-h of 20 Boulevard Diderot, in the cit-y of Paris, Republic of France, engineers, have invented an Antisparking Device for Dy- Inimollectlric Machines, of which the following is a full, clear, and exact description.

Rotary transformers are already known by means of which monophase or polyphase alternating currents can be transformed into continuous current of Variable tension by the simple lag of the brushes. In principle, these appliances consist of a rotor composed of a rin@ provided with coils, rings introducing tthe alternating currents, commutators and brushes collecting the continuous current` on the commutatore. Such a transformer is set forth in the French patent to Auvertand Ferrand #$23,126.

The useful fluxes generated by the coils form magnetic circuits which are completely closed in the ring itself. The coils, connec tions and the. position of the brushes are combined in such a manner that when the whole is in synchronous rotation, the brushes mounted on-the commutatore collect a practically continuous current the mean di erences of potential between the commutator brushes remains constantly of the same kind and at, a. certain mean value, which mean value moreover, may be regulated by simply shifting the brushes 'of these cornmutators.

The power of an apparatus of this typo is easily limited by the appearance ot' sparks at the commutatore: thc formation of sparks depends on the tension between the plates of the Comunitat-or, and also oir the. tension of reactance ofthe sections of t ie coil.

The permissible tension betavceu the plates of the commutator may be heightened by employing the well known means of connecting the sections of the coil to the plates of the commutator by the aid of resistance connections, but, in order to lessen the tension ot` reactance, it, is'necessary to reduc-e the self-induction of the sections of the coil., by preventing; the formation of the parasitic fluxes which are completed by the air in the vicinity of the ring, under the action of the intense and highly Yductuatiug currents traversing the commutator sections.

The subject of the present invention is a device enablingoarnsitic fluxes to be almost entirely7 suppressed in this type ot apparatus and consequently reducingr the tension of reactanceof the comlnutator sections to a very low figure, which tension forms the chief cause of the production ot sparks at the coiumutators. Y

in principle. the invention consists in sur-- rounding the ring of the transformer with a metallic casing. in such a manner that the parasitic fluxes are con'ipellecl to traverso metallic screens in which are generated secondary currents tending to nullit'y these parasitic fluxes;

Figures l, 2. 3 and 4 represent. typical examples of various forms that. can no given to these screenssurrounding the ring of a` transformer of alternating currents into continllous current. and Fig is a diagrammatic perspective View of the improvement. in place.

In Figs. l and 2 the ring is provided with four screens a, b, c, d; the screens a and o are cylindrical, the screens c and nl are cheeks applied against the outermost plates of the. ring. Fig. 1 shows part of the coil e, Fig. 2. which is a section shows only one turn of the coil.

lt is easily seen that the magnetic circuit which tends to form around the turn heir completed by the air in the vicinity ot the rim. is compelled to traverse the screens Q c, fl. lt sets up seconda y currents'y in these screens, and everything proceeds the case of a statical transit-owner with A;. turn of the coil as primary incnzl with the .secondary member formed by the me tallic screens of extremely low resistance in short circuit. lt, is known that an arrangev meut of this kind corresponds to the almost complete suppression of the sel'linduclion of the primary member, that is to say. in this particular instance of the turn of the coil. Hence, the commutation can be effect ed with a tension of reactance that is weaker in proportion as the section chosen for the screens is greater.

' Fig. 3 shows' another possible arrangement of the screens. fn ligure, the screens are three in number, a, c, oi which a is cylindrical, while the. two pieces o and c are identical and may be. tbe-y may be made in one piece (Fig. .li tb for bolting together the piet of the ruig.

It is necessary that the screens as a whole. should not constitute a completed circuit con centric'"`\vith the coil that is to say, surrounding the ring, for, under the action of the principal fluxes, whose circuits areentirely completed in the ring', secondary' currents of considerable importancewould be set up in these screens, the result being equivalent to the short ircuting of the generating source of the alternating currents.

It is understood that '.'the arrangements illustratedein the drawings yaccompanying this application are merely givenas tpicall examples, since `the screens mayA be,s aped in any other.- Way considered likelytoincrease facility of construction, g

The invention may be applied directly to all rotary transformers for transforming monophase or polyphase alternating currents into continuous current of variable ten` sion by the simple lag-ofthe brushes, and 'of which the useful magnetic circuits are entirely 'completed in a ring".`A For a given size, it ena les the power-vof these machines to be considerably augmented without any appreciable increase of weight, because 1tl enables more powerful currents to be' dealt with per line of brushes on the commutatore While almost entirely suppressing the tension of rcactance of the conunutated sections.

In Fig. 5d indicates the screen surrounding the ring, e the coil, the collector, and g the shaft. Two rings and are .mounted on th shaft to which are connected the coils e, andthe said ring's are connected-to the secondary oi a transformer t. The rotating part m, of a synchronous 'motor is also` mounted on the shaft, the stator ofthe said motor being energized vby a current coming from the dynamo n. Rings o and p are arranged on "the shaft, the said rings being connected to the coils of the rotating part and to the secondary of the transformer t.

Claims. I l, In an anti-sparking device for converters, an annular core, a-primary coil for said core, said coil being wound. so as t'o magnetize the core' circularly, and means for confining the useful magnetic fluxes to the core, said means comprising a plurality of magnetic screen members disposed externally of said core, said screen members being spaced apart.y

magnetize the core circularly, and means for confining the useful magnetic fluxes to the magneticscreen members disposed between the core and the primary coil, said screen members being spaced apart at their adja- `cent edges. l

ers, an annular core, a primary coil for said core, said coil being wound so as to'magnetize the'. core circularly, and. means for confining the useful magnetic fluxes to the core, 'said means comprisin a pair of concentric, cylindrical, magnet c screens, one of said screens bein arranged inside and the 'other outside o the core, and annular screens, one at eachside of the core, the screens being spaced apart at their adjacent ed es.

Ln an anti-sparking device for converters, fin-*annular core, a primary coil for said core, said coil being wound so as to magnetize the core circularly, means for conlining the useful 'magnetic fluxes to the. core, said means comprising a pair of concentric, cylindrical,I magnetic screens, one of' said Vscreens, being arranged inside and the other outside ofthe core, and annular screens, one at each side' of the core, the screens being disposed between the core and the primary coil and being spaced apart at their adjacent edges. A

The foregoing s ecification of our device for effecting Vtlie almost complete suppressionl of arasitic fluxes in rotary transformers, vv thout air-gap, for converting monophasel and polyphase alternatlng currents intolcontirluous current signed by us. In testimony whereof We have signed our names to this specification in the p resence of tvvo subscribing witnesses.

Louis RENE AUYERT. ALPHoNsE Francois ERNEST FERRAND.

Witnesses:

.GEonGEs Ci-r ARLES CoQUE'r,

'REN J ULi 1 CHIRIQT.

3. In an anti-'sparking device for convertsaid core, said coil being wound so asnto i core, said means comprising a plurality ofl 

